The present application is a U.S. National Stage application of International Application No. PCT/EP99/02976, filed May 3, 1999, which claims priority under 35 U.S.C. xc2xa7119 of German Application No. 198 20 951.7 filed May 11, 1998.
1. Field of the Invention
The invention relates to a composite fabric web for reinforcing soil comprising of a textile lattice and a water-permeable flat textile structure joined to the lattice.
2. Discussion of Background Information
Geotextile composite fabric webs of this kind are known from the U.S. Pat. No. 4,472,086. The lattice as well as the flat textile structure, formed by a mat, of the known composite fibrous web have a stretchability of less than 5%. Further, the mesh width of the lattice is relatively small. These geotextile composite fabric webs are designated and used for the reinforcement of layers of black top. Further, for reinforcing soil layers, lattice structures of highly modular polyester threads are known whose mesh width lies between 20 mm and 50 mm which are particularly suitable for securing topographical steps, for reinforcing the upper layer of traffic surfaces, earth dams, noise protection barriers, and the like.
The present invention is based on as aspect of creating a geotextile composite fabric web of the type mentioned at the outset that not only achieves a good reinforcement by its incorporation but also allows the subsoil situated underneath the textile composite fabric web to be consolidated quickly and reliably
According to an aspect of the invention a composite fabric web for reinforcing soil layers is provided. The web comprises a textile lattice and a water-permeable flat textile structure connected to the lattice. The lattice comprises of highly tension resistant strips having a width of at least 4 cm positioned in the longitudinal direction of the composite fabric web at a distance from one another of at least 30 cm and of highly tension ""resistant second strips having a width of at least 4 cm, positioned laterally to the first strips at a distance from one another of at least 30 cm and being connected to the first strips at the crossing points in a slip-resistant fashion, and in that the flat textile structure comprises of a tear-resistant material stretchable by at least 25%, preferably 35% to 80%, e.g., nonwoven, knitted materials or the like, and is positioned above the lattice.
After spreading the composite fibrous web according to the invention onto the level of the subsoil to be consolidated, a layer, 30 to 60 cm thick, of sand, gravel, rubble, and, optionally, also broken rocks, is dumped and this layer is compacted, for instance, via rolls and tampers. Here, the accumulated layer presses the highly stretchable flat textile structure, in particular a non-woven, into the stretchable, aqueous base, with pore water being pressed upward through the filtering flat textile structure. In compacting the filling, the stretchable flat textile structure bulges downward between the longitudinally and laterally positioned strips of the lattice by which a strong interlocking is achieved between the filling and the base. At the same time, the contact surface increases between the base and the filtering flat textile structure so that the extraction of water from the aqueous base is accelerated as well. After adding a second and, optionally, a third filling, further compacting can occur with increased pressure without the risk of the downward bulging textile flat structure tearing, because bridges or arches form above the empty areas of the lattice inside the filling resting on the strips of the lattice. When the filling is thicker than the clear width of the areas of the lattice, the compacting forces essentially effect only the strips of the lattice so that a further increase of stress in the stretchable flat textile structure is no longer to be expected. The stretchable, water-permeable, and filtering flat textile structure can be a knitted or a woven web, preferably a formed fabric, however, that is needled for reinforcement. This non-woven can be 2 to 6 mm thick and has a protecting function for the load-bearing strips of the lattice during the compacting of the filling.
With the aid of the fibrous composite web, the consolidation of the base of roadways and traffic areas can be considerably improved and accelerated. At the same time, a reliable interlocking is achieved between the base and the filling, although a filtering layer is positioned between the base and the filling which prevents the clay-type parts of the base from reaching the granular and hydrophobic filling. Finally, a strong reinforcement is achieved in the layer in which the base is connected with the filling.
According to an aspect of the present invention, a composite fabric web for reinforcing soil layers is provided, comprising a textile lattice; and a water-permeable flat textile structure connected to and positioned above said. lattice. The textile lattice includes a plurality of highly tension resistant first strips, having a width of at least 4 cm, positioned in a substantially longitudinal direction of said composite fabric web at a predetermined distance from one another of at least 30 cm, and a plurality of highly tension resistant second strips, having a width of at least 4 cm, positioned substantially laterally to said first strips at a distance from one another of at least 30 cm and being connected to said first strips at crossing points in a slip-resistant manner.
According to another aspect of the invention, the flat textile structure includes a tear-resistant material which is stretchable by at least 25% of an unstretched length of the tear-resistant material. According to a further aspect of the present invention, the flat structure includes a tear-resistant material which is stretchable by at least 35% of the unstretched length of the tear-resistant material. In another aspect of the invention, the tear-resistant material is stretchable up to about 80% of the unstretched length of the tear-resistant material.
Other aspects of the invention include, a tear-resistant material comprises a nonwoven, knitted material. According to a further aspect of the present invention, a clear width between the strips is 30 cm to 60 cm. Additionally, other aspects include the width of the strips being between 6 and 12 cm. Other aspects include strips which include of one of highly modular threads or fibers having a tensile resistance of more than 15 kN. In another aspect of the present invention, the strips have a tensile resistance of more than 30 kN.
According to a further aspect of the present invention, the textile lattice has a tensile resistance of between 50 and 150 k N/m in the longitudinal direction and in the lateral direction. In another aspect of the present invention, the strips of the lattice comprise woven of highly modular warp threads and connecting weft threads. According to a further aspect of the present invention, the strips include thread layers with highly modular warp threads running in the longitudinal direction that are sewed together.
In another aspect of the present invention, clear areas are formed by the lattice are rectangular-shaped. According to a still further aspect of the present invention, the clear areas are square-shaped. According to a different aspect, wherein, at least at one edge of the composite fabric web, rectangular areas are provided whose length is at least twice as long as the length of the other clear areas. According to another aspect of the present invention, wherein the stretchable flat textile structure is a needled nonwoven fabric of syhthetic fibers with a thickness of 1.5 to 6 mm and a tear resistance of at least 1.5 kN piston force. Further aspects of the invention include, wherein the stretchable flat textile structure is a needled nonwoven fabric of synthetic fibers with a thickness of 1.5 to 6 mm and a tear resistance of at least 1.5 kN piston force according to DIN 54307 and DIN EN 776.
Other aspects include, wherein, on edge areas of the composite fabric web, coupling devices are provided at the laterally running second strips that cooperate with complementary coupling devices of a neighboring composite fabric web.
According to other aspects of the present invention, wherein the coupling devices include one of hooks and eyelets and the complementary coupling devices include the other of eyelets and hooks, respectively. According to another aspect of the invention, the web is about 8 to 12 m wide and is folded in the area of its longitudinal center into a 4 to 6 m wide double web and then coiled into a roll. According to a further aspect of the invention, the composite fabric web is folded in such a way that the stretchable flat textile structure lies inside and the longitudinally running strips of one half are positioned between the strips of the other half.
According to a still further aspect of the invention, a process is provided for consolidating a soil layer. A composite fabric web including, a textile lattice having, a plurality of highly tension resistant first strips, having a width of at least 4 cm, positioned in a substantially longitudinal direction of the composite fabric web at a predetermined distance from one another of at least 30 cm, and a plurality highly tension resistant second strips, having a width of at least 4 cm, positioned substantially laterally to the first strips at a distance from one another of at least 30 cm and being connected to the first strips at crossing points in a slip-resistant fashion, and a water-permeable flat textile structure connected to and positioned above said lattice, is provided. The process includes spreading the composite fabric web onto the soil of a soil layer to be consolidated; compressing the composite fabric web with a filling of a mixture of at least one of sand, gravel, rubble, and broken rock in a layer of 30 to 60 cm, but not higher than a clear width of the lattice areas; compressing the filling first statically and then dynamically with a contact pressure of 50 to 150 kN/m2; applying a second layer of filling of at least 30 cm; and further compressing the second layer.
According to another aspect of the invention, the second layer is compressed with an increased force. In yet another aspect of the invention, the process is used for consolidating a soil layer for a roadway. According to another aspect of the present invention, the process includes installing a second composite fabric web next to a first installed composite fabric web, which overlaps the first composite fabric web to such an extent that the areas at the left or right edge of the second composite fabric web are positioned above the areas at the right or left edge of the first composite fabric web.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.